Sheet metal shears with compensation for knife drum tilt



Dec. 26, 1967 K. GREIS ETAL 3,359,845

SHEET METAL SHEARS WITH COMPENSATION FOR KNIFE DRUM TILT Filed Oct. 25, 1965 I s Sheets-Shegt 1 Dec. 26, 1967 GRE|$ ETAL 3,359,845

SHEET METAL SHEARS WITH COMPENSATION FOR KNIFE DRUM TILT Filed 061. 23, 1965 :5 Sheets-Sheet 2 Dec. 26; 1967 K. GREIS EYTAL. v 3,359,345

SHEET METAL sHEARs WITH COMPENSATION FOR KNIFE DRUM TILT Filed Oct. 25, 1965 s Sheets-Sheet H WITIH NINAPIQII m m T u .M

United States Patent 3,359,845 SHEET METAL SHEARS WITH COMPENSATION FOR KNIFE DRUM TILT Karl Greis and Paul Hamacher, St. Ingbert, Saar, Germany, assignors to Verwaltungsgesellschaft Mueller 8: N eumann oifene Handelsgesellschaft, St. Inghert, Saar, Germany Filed Oct. 23, 1965, Ser. No. 503,582 Claims priority, application (geirmany, Nov. 17, 1964,

8 Claims. 61. 83-556) ABSTRACT OF THE DISCLOSURE This invention relates to sheet metal shears of the guillotine type for trimming sheet metal strips and plates and relates more particularly to guillotine type shears for a double shears installation, comprising two oppositely disposed individual shears for trimming both edges of a sheet metal strip and particularly plates.

The guillotine type shears have a stationary lower knife and a movable upper knife being guided before and during the return stroke to a larger knife interval than during the cutting stroke in derivation of the shearing drive.

The pivot axis of the knife support is mounted in hori- Zontally' guided bearing members and the arrangement for theknife retraction before the return stroke consists of two plate type toggle lever linkages which are articulated On one side to the bearing members and on the other side to the shears housing and reversible drives are connected to the articulated joints. This type of mechanism is described in US. Patent 3,154,988, issued on Nov. 3, 1964.

The use of toggle lever linkages as means for retracting the shears requires that toggle levers are in a straight position during the cutting action in order to transfer the horizontal component for the cutting pressure directly into the shears frame. However, the straight position is obtained only in a very advanced position of the bearing members which is oriented toward the metal sheet and which is adjustable by means of abutment pieces which may be changed to adjust the knife gap. This means that the toggle lever linkages can no longer assume a straight position when the bearing members are set back from the metal sheet in their front abutment position for adjusting a larger knife gap. In this case a part of the horizontal components of the cutting pressure must go into the driving arrangement of the periodically operated knife return.

It is therefore an object of the invention to make the adjusting device for the knife return independent of the knife gap adjustment and to keep it free of the components of the cutting pressure. This object of the invention is obtained by appropriate means which make it possible to provide for each knife gap setting a straight position of the toggle lever linkage.

It is another object of the invention to provide a continuous trimming of metal sheets as the horizontal component of the cutting pressure is always taken up or transferred by toggle lever linkages in a straight position.

The invention provides also means by which the joint between two toggle lever linkage parts is avoided and also the overall width of the shears is reduced.

Another object of the invention is the provision of sheet metal shears for opposite edge trimming operations wherein the knife supports of the movable knife are angularly adjustable to the advancing direction of the metal sheet to be trimmed.

These and other objects and features of the invention will be described in greater detail hereinafter in connection with the accompanying drawings illustrating an embodiment of the invention by way of example only and in which:

FIGURE 1 shows a vertical section through the shears in a bearing plane of the drum type knife support along line II of FIGURE 3.

FIGURE 2 shows a part of the driving device for the knife retraction arrangement in section along line IIII of FIGURE 1.

FIGURE 3 shows a rear view of the shears in the direction of the arrow A in FIGURE 1 and a bearing side in section along line III-III of FIGURE 1, and

FIGURE 4 shows a section along line IV1V of FIG- URE 3 on an enlarged scale.

In reference to FIGURE 1 four upper knives 1 are mounted in a drum type knife support 2 whose outline is shown in a dash-and-dot line showing the arrangement of only two upper knives 1 and 1a. The knife support is located in front of the. drawing plane. An upper knife 1a cooperates with a stationary lower knife 15 for the purpose of edge trimming a metal sheet 16.

The knife support 2 is mounted for free rotation over the shaft 3 in two lateral bearing blocks 5 and is reversibly driven in a known manner from a crank shaft 9 over push rods which are not shown in the drawings.

Each bearing block 5 is slideably mounted in guides 14a of the shears frame 14. For a periodic displacement of the bearing blocks 5 and thus of the knife drum 2 during the return stroke away from metal sheet 16 a retraction device is employed which is mounted on each bearing 5 and will be more clearly explained hereafter with reference to FIGURE 4. The bearing block 5 has two fork-like bearing eyes 5a in which over roller bearings 39, 31 an excentric shaft 32 is journalled. At the excentric part 32a of the excentric part 32 which replaces a link of the toggle lever disclosed in the earlier arrangement, a link 17 is connected which is articulated to a linkage shaft 19. The linkage shaft 19 is mounted in a forklike adjusting piece 33 which is non-rotatably connected to a threaded spindle 34. The spindle 34 sits in a rotatable but non-.slideable nut 35 which carries at the forward end a bevel gear 35a. The bevel gear 35:: meshes with a bevel gear 38, 39. The worm wheel 38 and the Worm 39 are mounted in housing 40 which is fixed to an outer wall of the shear frame as shown in FIGURE 3. It may also be seen from FIGURE 3 that the worms 39 of both bearing sides may be driven by a motor 41 over common drive shaft 42. By means of the magnetic powder coupling 43 the worm 39 of the right bearing side may be disconnected.

Due to the fact that the linkage shaft 19 of the link 17 may be displaced over the parts 34 to 43 in the direction of the guides 14a of the bearing blocks 5 the knife gap may be adjusted without a pivoting of the link 17 or the excentric portion 32a of the excentric shafts 32. When the magnetic powder coupling 43 is disconnected the knife drum 2 may be somewhat inclined to metal sheet 6 over the knife gap adjusting installation of the left bearing side which may be necessary in order to avoid a stepped cutting line in trimming the edges of the metal sheet. Due to the disconnection of the magnetic powder coupling 43, the bearing on the right side and its knife gap adjustment are disconnected so that the motor 41 and the threaded nut 35 operate only the bearing side on the left, for the left bearing block 5. The left block is adjusted in one or the other direction. This provides an adjustment of the movable knife relative to the sheet edges in a horizontal plane.

This individual adjustment of the knife support for angularly setting the knife relative to the advancing direction of the sheet is a very important development in edge trimming operations with oppositely disposed trimming shears. Independently of the disclosed embodiment it is within the scope of the invention that in connection with other types of trimming shears the movable knife support with its knife may be set angularly to the advancing direction of the sheet to be trimmed. In a broader sense one of two trimming shears of a shearing line may be pivotally mounted and adjusted for the angular setting of the movable knife.

The knife retraction arrangement for displacing the upper cutting knife during the return stroke away from the metal sheet 16 works independently of the knife gap adjustment in that on the outside of the excentric shafts 32 a crank arm 45 each is non-rotatably secured (FIG- URE 4) to which vertically disposed push rods 46 are connected. The crank arms 45 are actuated during the return stroke of the upper cutting knife 1a in a reciprocating manner and this is obtained by means of one cam wheel 47 each fixed to the main drive shaft 9 by means of which one fork lever 49 each mounted at 48 on the shears frame cooperates over two sensing rollers 50, 51 at whose fork the push rods 46 are movably connected. If for example the main drive shaft 9 rotates in the direction of the arrow indicated the fork levers 49 execute a movement in a clockwise direction whereby the push rods 46 rise. Over the crank arms 45 the excentric portions 32a of the excentric shafts 32 are displaced from a horizontal dead center position in such a Way that the bearing blocks 5 and thus the knife drum 2 is moved away from the metal sheet 16.

Upon a further rotation of the main drive shaft 9 the push rods 46 move down again into the starting position in which the cutting forces from the bearing blocks 5 are absorbed over the excentric members 32 located in the dead center position, the links 17, the linkage shafts 19 and finally by the shears frame 14. A variation of the knife gap through the knife gap adjustment 34 to 43 has hardly any effect on the position of the excentric member 32a in view of the vertical position of the push rods 46 so that the actual knife retraction drives 45 to 51 are always free of cutting forces independently of the knife gap adjustment.

What is claimed is:

1. Sheet metal shears for trimming sheet meal strips and plates adapted for double shears installations comprising in combination two oppositely disposed individual shears, each of said shears including a shaft disposed parallel to the path of movement of said sheet, a movable knife support carried by said shaft, said support including at least one radial arm, a movable knife mounted on said arm, a stationary knife mounted for cooperation with the movable knife on said arm, a reciprocating drive means for oscillating said knife support, bearings for said knife-support-shaft, guideways for slidably mounting said bearings, power means including toggle linkages connected to said bearings and to a pivot shaft each disposed at each shears frame for moving said bearings, shaft, support and movable knife toward and away from said fixed knife to prevent contact between said movable knife and the cut edge of said sheet during the return stroke of said movable knife, and means for moving said pivot shafts, toggle linkages, bearings, shaft, support and movable knife independently of said power means for adjusting the knife gap with said toggle linkages in a straight position.

2. Sheet metal shears according to claim 1 wherein the links connected to said bearings are each replaced by an excentric shaft on whose excentric portion the link supported by said pivot shaft is connected and wherein reciprocating drives engage at the excentric shafts to carry out a periodic movement of the excentric points for varying the distance between said shaft of said movable knife support and the fixed point.

3. Sheet metal shears according to claim 2 wherein the excentric shafts are movable by push rods over crank element-s fixed thereto, said push rods being driven each by a cam disc mounted on the main drive shaft over fork levers journaled at the shears frame.

4. Sheet metal shears according to claim 2 wherein the pivot shafts engaged by the links are mounted in setting pieces which are selectively movable together or at least one of them relative to the shears frame.

5. Sheet metal shears according to claim 4 wherein the setting pieces are non-rotatably connected to threaded spindles whose nuts are rotatably operated over each a worm and bevel gear drive by a driving shaft common to both bearing sides of said support shaft and separable by a magnetic coupling.

6. Sheet metal shears for trimming metal sheets and plates adapted for double shears installations comprising two oppositely disposed individual shears, each of said shears including a movable knife support with a movable knife, a stationary knife mounted for cooperation with each of the movable knives, and means for setting one of said knife supports relative to the other of said knife supports in a horizontal plane and relative to the trimming edge of the sheet.

7. Sheet metal shears as set forth in claim 6, further comprising means for moving said movable knives for adjusting the knife gap between said movable knives and said fixed knives.

8. Sheet metal shears as set forth in claim 7 wherein said means for setting utilizes a portion of the means for adjusting the said knife gap.

JAMES M. MEISTER, Primary Examiner. 

1. SHEET METAL SHEARS FOR TRIMMING SHEET METAL STRIPS AND PLATES ADAPTED FOR DOUBLE SHEARS INSTALLATIONS COMPRISING IN COMBINATION TWO OPPOSITELY DISPOSED INDIVIDUAL SHEARS, EACH OF SAID SHEARS INCLUDING A SHAFT DISPOSED PARALLEL TO THE PATH OF MOVEMENT OF SAID SHEET, A MOVABLE KNIFE SUPPORT CARRIED BY SAID SHAFT, SAID SUPPORT INCLUDING AT LEAST ONE RADIAL ARM, A MOVABLE KNIFE MOUNTED ON SAID ARM, A STATIONARY KNIFE MOUNTED FOR COOPERATION WITH THE MOVABLE KNIFE ON SAID ARM, A RECIPROCATING DRIVE MEANS FOR OSCILLATING SAID KNIFE SUPPORT, BEARINGS FOR SAID KNIFE-SUPPORT-SHAFT, GUIDEWAYS FOR SLIDABLY MOUNTING SAID BEARINGS, POWER MEANS INCLUDING TOGGLE LINKAGES CONNECTED TO SAID BEARINGS AND TO A PIVOT SHAFT EACH DISPOSED AT EACH SHEARS FRAME FOR MOVING SAID BEARINGS, SHAFT, SUPPORT AND MOVABLE KNIFE TOWARD AND AWAY FROM SAID FIXED KNIFE TO PREVENT CONTACT BETWEEN SAID MOVABLE KNIFE AND THE CUT EDGE OF SAID SHEET DURING THE RETURN STROKE OF SAID MOVABLE KNIFE, AND MEANS FOR MOVING SAID PIVOT SHAFTS, TOGGLE LINKAGES, BEARINGS, SHAFT, SUPPORT AND MOVABLE KNIFE INDEPENDENTLY OF SAID POWER MEANS FOR ADJUSTING THE KNIFE GAP WITH SAID TOGGLE LINKAGES IN A STRAIGHT POSITION. 